This application relates to a structure for electrically grounding fan blades for use in a gas turbine engine.
Gas turbine engines are known, and typically include a fan delivering air into a compressor section. In the compressor section, the air is compressed and then delivered into a combustion section. The compressed air is mixed with fuel and burned in the combustion section. Products of this combustion pass downstream to drive turbine rotors.
The fan blades are subject to a large volume of air moving across an airfoil. This can build up a large static electric charge. Conventionally, the fan blades were formed of a conductive metal that was grounded to a hub that mounts the fan blade. As such, the charge would dissipate.
More recently, fan blades have become larger. One factor allowing the larger fan blades is the use of a gear reduction between a turbine driven spool, which drives the fan blade, and the spool. The gear reduction allows a single turbine rotor to drive both a compressor section and the fan, but at different speeds.
As the size of the fan blade has increased, its weight has also increased. As such, efforts have been made to reduce the weight of fan blades. One modification is to change the material for the fan blade from titanium to aluminum. The aluminum fan blades have been covered with a polyurethane coating and fabric wear pads to protect the aluminum. These materials have insulation qualities and, thus, the blade may not be electrically grounded to a rotor.